Shaima Awadh Hashem1,2, Michalis Georgiou1,2,3, Robin R. Ali1,2,4 and Michel Michaelides1,2 1UCL Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom 2Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, United Kingdom 3Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA 4Centre for Cell and Gene Therapy, King's College London, London WC2R 2LS, United Kingdom Correspondence: michel.michaelidesucl.ac.uk

Retinitis pigmentosa GTPase regulator (RPGR) gene variants are the predominant cause of X-linked retinitis pigmentosa (XLRP) and a common cause of cone-rod dystrophy (CORD). XLRP presents as early as the first decade of life, with impaired night vision and constriction of peripheral visual field and rapid progression, eventually leading to blindness. In this review, we present RPGR gene structure and function, molecular genetics, animal models, RPGR-associated phenotypes and highlight emerging potential treatments such as gene-replacement therapy.